We (a group of 5 people of whom 2 power wheelchair users) recently used the service and it was great! We booked everything through their website ( https://www.seouldanurim.net/en/index ), which was very convenient. When you do the bookings there is a calendar where availability of equipment or services is shown. They reply as well to any inquiries through email. Just note that in case of transfer between airport and hotel, only one way is offered (from the airport to your hotel).